Add resizing for all text elements as for TextAnnotation

[topialla]

Text elements in tasks or at gateways can have issues with proper spacing and readability.
So far I often edit the svg to properly align/size the text, but of course then I cannot reedit within this awesome tool ;-)

Describe the solution you'd like
For starters, it would be very helpful, if I could resize the textbox for gateways similar as can be done with TextAnnotations.
Longer term text sizing and markdownsupport for simple formatting would be great.

Describe alternatives you've considered
So far, I always use inkscape to edit the svg giving svg_A. Then, if needed, I change the bpmn in bpmn.io and export a new svg svg_B. Then I open svg_B, copy the changed parts, delete the changed parts from svg_A and use paste in place.
This is quite cumbersome.

[barmac]

Thank you for creating this issue.

So if I get it correctly, you'd like to be able to take this:

and transform it into something like this:

and generally be able to resize free-floating labels.

I think this is a valid feature request. The BPMN standard allows for that so I don't see a reason why we shouldn't have it. Feel free to create a pull request and I can support you if you encounter any roadblocks.

[topialla]

Yes, well summarized! Thank you.
I do not have time in the upcoming weeks, but will give it a try, or at least mention, when I start to try.

[smbea]

I made some progress on this but wasn't able to finish it. I will move it back to backlog for now. Current progress is here: https://github.com/bpmn-io/bpmn-js/tree/1513-resize-external-labels

[Ruandv]

What else is still oustanding that I can assist with on this issue?
I have pulled the branch mentioned above and got it up and running. Everything seems to be working as explained

[barmac]

I'd expect the label bounds to follow the text after resize. So if you make the label wider, the bounds should shrink vertically.